Engines may utilize a turbocharger or supercharger to compress ambient air entering the engine in order to increase power. Further, engines may recirculate a portion of exhaust gas from an exhaust passage to an intake passage, referred to herein as exhaust gas recirculation (EGR). In low pressure (LP) EGR, exhaust gas is routed from downstream of a turbine of the turbocharger to upstream of a compressor of the turbocharger. LP EGR may result in water condensation before the compressor, thereby increasing a risk of compressor wheel damage. In high pressure (HP) EGR, exhaust gas is routed from upstream of the turbine to downstream of the compressor. HP EGR may reduce condensation at the compressor; however, HP EGR may have flow limitations when boost pressure is higher than turbine backpressure. Other attempts to address the HP EGR and LP EGR system limitations discussed above may include a dual EGR system utilizing both HP and LP EGR systems. However, dual EGR systems may be costly.
In one example, the issues described above may be addressed by a system for introducing exhaust gases from an exhaust gas recirculation (EGR) system and to a compressor, downstream of a compressor blade. Specifically, a compressor of a turbocharger may include a compressor wheel rotatable about a central axis of the compressor and an EGR inlet volute. The compressor may further include a volute positioned within a casting of the compressor, the volute including a diffuser. The EGR inlet volute may include an injection port coupled to the diffuser at a position proximate to a trailing edge of the compressor wheel. Thus, exhaust gases from the EGR inlet volute may mix with intake air within the diffuser, downstream of the compressor wheel. Air flow velocities within this upstream region of the diffuser may be relatively high while air pressures may be lower than further downstream in the diffuser and volute. Introducing EGR in this way may reduce the EGR flow limitations of traditional HP EGR systems while also increasing durability of the compressor wheel.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.